This invention relates to a thermal switch device comprising a thermal reed switch assembly and an insulator case containing the thermal switch assembly, and in particular, to a mounting structure of the thermal reed switch assembly into the case.
A thermal switch device is well known in the art which comprises a thermal reed switch assembly contained in an insulator body. The thermal reed switch assembly comprises a reed switch having a pair of reeds and a temperature-sensitive magnetic structure mounted on the reed switch. The temperature-sensitive magnetic structure comprises at least one temperature-sensitive magnetic ring or cylinder and at lest one cylindrical permanent magnet. The temperature-sensitive magnetic ring has a Curie point at a desired temperature, and exhibits magnetism and paramagnetism at lower and higher temperatures than the Curie point, respectively. Therefore, the temperature variation of the temperature-sensitive magnetic ring around the Curie point changes flow of the magnetic flux of the permanent magnet through the paired reeds of the reed switch to control ON/OFF operation of the reed switch. Thus, the circumferential temperature of the thermal reed switch assembly can be detected as the ON/OFF state of the reed switch.
In a conventional structure of a thermal switch device of the type as described above, the thermal reed switch assembly is contained in an insulator body of such as synthetic or plastic resin as molded by the mold-in process. A lead frame is connected to the paired reeds before the molding operation. A frame portion of the lead frame is cut out after completion of the molding operation. Thus, two lead conductors or pieces are led out of the insulator body and are connected to the reeds, respectively.
The provision of the lead frame results in an unstable positioning of the reed switch assembly in a mold during the molding operation. This makes it difficult to produce the thermal switch device having a constant thickness of the insulator body surrounding the thermal reed switch assembly. Accordingly, it is difficult to produce the thermal switch devices having a constant temperature-sensitive characteristics.